textproduct: Albany

WHAT HAS CHANGED

Winter Weather Advisories have been issued for Tuesday into Tuesday night most higher terrain areas outside of the southern Adirondacks, as well as the Lake George-Saratoga region, Mohawk Valley and all of southern VT where a wintry mix of snow, sleet and freezing rain is expected. This area is where there is higher confidence for a wintry mix including some freezing rain to occur, especially Tuesday afternoon/evening.

KEY MESSAGES

1) Moderate to high confidence for snow/wintry mix to occur across much of the region Tuesday into Tuesday night, which may change to plain rain in some valley areas from Albany southward by late Tuesday afternoon. Main impacts will be potentially hazardous travel conditions for the Tuesday evening commute.

2) Active weather pattern with additional precipitation chances for Wednesday night into Friday, some of which could be mixed precipitation (including freezing rain) across the southern Adirondacks, southern VT and the Berkshires.

3) Warmer weather, combined with occasional rainfall, increase the threat for snowmelt, river/creek ice breakup/jams, and possible flooding later this week into early next week, though there remains considerable uncertainty regarding exact rainfall/snowmelt amounts and therefore extent of flooding potential.

DISCUSSION

KEY MESSAGE 1...

After another cold night tonight with min temps dropping into the single digits above and below zero for some areas, developing warm front will approach from the south as a wave of low pressure develops along the front over the Ohio Valley and tracks east along the front. This will allow precipitation to develop across across the eastern Catskills/mid Hudson Valley Tuesday morning, before expanding north and east to encompass most areas along and south of I-90 by midday, and across the southern Adirondacks, Lake George/Saratoga region and southern VT by early-mid afternoon.

Initially, mainly light snow is expected. Model soundings suggest the best lift will be below the dendritic growth zones for areas south of I-90, suggesting snow accumulations should be light with ratios generally less than 10:1. However, with such cold ground temperatures, untreated ground surfaces will will become slippery in some areas. As the precipitation expands northward in the afternoon and into a deeper layer of cold air, the lift may occasionally intersect the dendritic growth layer and result in slightly more efficient snowfall accumulations for areas mainly north of I-90, where 1-3 inches and some locally greater amounts (mainly across higher terrain) will be possible.

Warmer air aloft will gradually track into the region, allowing precipitation to mix with, or change to sleet for areas near and south of I-90 during the afternoon, and eventually plain rain for valley areas from Albany southward by late afternoon. Across the eastern Catskills, as well as the Berkshires and NW CT, enough cold air may linger to allow for some areas of freezing rain during Tuesday afternoon/evening.

Eventually, even areas north of I-90 should mix with and/or change to sleet by late afternoon/early evening, with some areas of freezing rain possible early Tuesday night. The chance for freezing rain will be less across the southern Adirondacks, which is why this area has been left out of the Winter Weather Advisories at this time.

Precipitation should taper off late Tuesday night/early Wednesday morning, possibly as some freezing drizzle before ending prior to daybreak Wednesday.

Main impacts from the snow/wintry mix will be potentially hazardous travel conditions for the Tuesday evening commute within the advisory areas.

KEY MESSAGE 2...

Active pattern continues with frontal boundary draped just south of the region for Wednesday night through Friday, as a couple of waves of low pressure track along the boundary. The first wave looks to bring mainly rain for Wednesday night into early Thursday. However, enough cold air may persist across portions of the southern Adirondacks, upper Hudson Valley and southern VT to allow for some sleet/freezing rain to occur.

Another, potentially stronger wave looks to track east late Thursday into Friday. Again, some sleet/freezing rain will be possible across northern areas as some colder air across southeast Canada may drain southward as the wave of low pressure approaches. 13Z/Mon NBM 24-hour probs ending 7 PM Friday for > 0.10" ice accretion at 30-40% for higher elevations of the southern Adirondacks/southern VT, with similar probs for >0.25" ice at 10-20%. So trends will need to be watch for freezing rain and some ice accretion potential in these areas, with some sleet/freezing rain even possible as far south and west as the Lake George/Saratoga region and eastern Mohawk Valley.

KEY MESSAGE 3...

Aforementioned active pattern will bring periods of rain/mixed precipitation to the region late this week into next weekend, though there remains some uncertainty on where greatest amounts occur, and will ultimately depend on the placement of the frontal system and track of low pressure waves along the front. 13Z/NBM 72-hour probs ending 7 AM Friday for QPF > 1 inch is 40-70% for areas near and south of I-90 (greatest across the SE Catskills), and similar probs ending 8 AM Sunday are 40-60%, however greatest across the SW Adirondacks, Mohawk Valley and Saratoga region (due to another potential system for Saturday into Sunday).

In addition to the rainfall, warmer temperatures are forecast across the region, especially valley areas south of I-90, where probs for max temps >50F through 8 PM Saturday are 60-90% Saturday-Sunday, and even higher for Monday (80-100%). They remain lower across the SW Adirondacks through this weekend (10-30%), then increase Monday to 20-50%. The uncertainty is greater across the southern Adirondacks, upper Hudson Valley and southern VT as the nearby frontal boundary may waver north and south, limiting the warming potential through Sunday across these areas.

The combination of several periods of at least moderate rainfall, and warmer temperatures will increase the chances for snowmelt/runoff and ice breakup and possible jams on area rivers/creeks, starting later this week into the weekend, and increasing further early next week with potentially widespread warmer temps.

There remains some uncertainty on just how much rainfall occurs and extent of warming through this weekend, however initial indications are for the best potential overlap between warming, rainfall and resulting ice breakup through Sunday would be for areas south of I-90, including the eastern Catskills. Latest MMEFS suggest increased chances for at least minor river flooding across portions of the eastern Catskills, Mohawk River, and areas along the Housatonic River late this weekend into early next week. So, trends will need to be watched closely as we approach the weekend into early next week to better refine the potential for snowmelt, ice breakup and flooding.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

VFR conditions begin the TAF cycle for KGFL/KALB/KPSF/KPOU with some high clouds increasing ahead of a frontal boundary and a low pressure system between 09Z-13Z/Tue. The clouds will quickly thicken and lower after sunrise south and east of KALB with light snow developing and MVFR/IFR conditions in terms of visibilities 15Z-17Z/Tue for KPOU/KPSF...and the snow developing 16Z-18Z/Tue for KALB/KGFL. Expect widespread IFR conditions to continue through the afternoon into the early evening. The pcpn will mix with some pellets and rain for KALB/KPOU 22Z/Tue to 00Z/Wed. KPSF will see a wintry mix to sleet/freezing rain by 23Z/Tue. KGFL may hold mostly as snow until 04Z/Wed, but a brief mixture with/to freezing drizzle is possible. The pcpn should diminish 03Z-06Z/Wed with some patchy plain drizzle or freezing drizzle with IFR vsbys/cigs.

The winds will be light to calm to begin the TAF cycle and then will be southeast to south at less than 10 KT. The winds will become light and variable to calm after 00Z/Wed. LLWS may need to be added to some of the TAF sites this afternoon into early this evening, as the 2 kft AGL winds may increase to 30-35 KT with the sfc winds 5 KT or less.

Outlook...

Wednesday Night: Low Operational Impact. Slight Chance of FZRA. Thursday: Moderate Operational Impact. Chance of SHRA. Thursday Night: High Operational Impact. Definite SHRA. Friday: Moderate Operational Impact. Chance of SHRA. Friday Night: Moderate Operational Impact. Chance of RA. Saturday: Moderate Operational Impact. Chance of RA. Saturday Night: High Operational Impact. Likely RA. Sunday: No Operational Impact. NO SIG WX.

ALY WATCHES/WARNINGS/ADVISORIES

CT...Winter Weather Advisory from noon today to 5 AM EST Wednesday for CTZ001-013. NY...Winter Weather Advisory from noon today to 5 AM EST Wednesday for NYZ041-054-061-066-083-084. Winter Weather Advisory from 9 AM this morning to 3 AM EST Wednesday for NYZ038>040-047-048-051-058-063-082. MA...Winter Weather Advisory from noon today to 5 AM EST Wednesday for MAZ001-025. VT...Winter Weather Advisory from noon today to 5 AM EST Wednesday for VTZ013>015.